Display screen or portion thereof with transitional graphical user interface



FIG. 1 is a first image of a display screen or portion thereof withtransitional graphical user interface showing our new design;

FIG. 2 is a second image thereof;

FIG. 3 is a third image thereof; and,

FIG. 4 is a fourth image thereof.

The outer broken lines in the figures depict a display screen or portionthereof and form no part of the claimed design. The remainder of thebroken lines in the figures depict portions of the graphical userinterface that form no part of the claimed design.

The appearance of the transitional user interface sequentiallytransitions between the images shown in FIGS. 1-4. The process or periodin which one image transitions to another forms no part of the claimeddesign.

CLAIM We claim the ornamental design for a display screen or portionthereof with transitional graphical user interface, as shown anddescribed.